Cross-cultural adaptation and validation of the NASS outcomes instrument in Spanish patients with low back pain.

OBJECTIVES: The aim of the study was to evaluate validity, reliability, responsiveness and practicality of the NASS-AAOS (North American Spine Society--American Academy of Orthopaedic Surgeons) questionnaire in patients with low back pain. METHODS: The sample included 70 patients with herniated disk, stenosis, chronic low back pain of unknown etiology or acute low back pain. They were assessed twice before treatment (test--retest) and a third measure six months to one year afterwards. RESULTS: The mean time of administration was 24 and 20 min for the test and post-treatment evaluation, respectively. Cronbach's alpha coefficient was between 0.78 and 0.92 on the baseline test and 0.90 or higher on the post-treatment evaluation. The test--retest reproducibility was 0.95 (0.91--0.98) for 'neurological symptoms', 0.82 (0.63--0.91) for 'pain/disability' and 0.63 (0.25--0.82) for 'expectations'. The associations with other measures and clinical criteria were generally moderate to high and in the expected direction. The effect size for 'pain/disability' in combination with 'neurological symptoms' was 2.02 for patients who improved versus an effect of -0.09 in patients who were stable between test and retest; the area under the curve on this joint scale was 0.81 (0.69--0.90). CONCLUSIONS: The instrument is valid, sensitive to clinical changes and reliable for comparisons between groups, but further study is needed for its application in monitoring individual patients.

Adaptation of the lumbar spine to different positions in bicycle racing.

STUDY DESIGN: A radiologic and electromyographic study was done of the adaptation of the lumbar spine to high-performance cycling. OBJECTIVES: To evaluate changes in the lumbar spine produced by different cycling positions on different types of bicycles used during competition. METHODS: Three professional cyclists were observed to evaluate changes in the lumbar spine. Radiographs were obtained of the different positions adopted by the cyclists during competition, and changes in the angles of the lumbar spine were measured. An electromyographic study was done of the abdominal, lumbar, and thoracic paravertebral muscles. RESULTS: The cyclists' positions involved a change from discal lordosis to kyphosis. To obtain a more aerodynamic position, the cyclists flexed the hip and made the pelvis horizontal without changing disc angles. The contraction of paravertebral lumbar muscles was proportional to pedalling intensity and decreased in more aerodynamic positions. The tone of the paravertebral thoracic muscles depended on the extent of cervical hyperextension. Abdominal muscles remained relaxed in all bicycle positions and with all pedalling intensities. CONCLUSIONS: The changes observed could modify the normal biomechanics of the lumbar spine, but the overall mechanical load on the spine is reduced by shifting weight onto the upper limbs. The imbalance that occurs between the activity of flexor and extensor muscles could cause lumbar pain in persons without proper physical preparation.